const koa = require("koa");
const app = new koa();
app.use(async ctx=>{
    let callbackName = ctx.query.callback || 'callback'
    // 返回jsonp
    var obj ={
        name:"cheng",
        age:18
    }
    ctx.body = callbackName + `(${JSON.stringify(obj)})`
})
app.listen(8080)